From the prior art, folding rollers are known which comprise front and rear axial portions. During use, the rear axial portion extends in the region of a rear portion of a signature to be folded, whilst the front axial portion extends in the region of a front edge of a signature to be folded.
The rear axial portion comprises a recess which is capable of releasing the upper portion of the signature to be folded in order to prevent occurrences of creasing of the downstream portion of the folded booklet.
Known folding rollers are capable of gripping the central portion of the booklet in the region of the front edge thereof in order to fold the booklet.